Of course it was reckless and unethical, but it also seems like kind of an unnecessary study. There have been lots of population exposures to radiation before then, and many more since, and there were ample ways to gather data from those. And, if absolutely necessary, rhesus monkeys are close enough for government work. With that, and with perhaps some extrapolation and translation of data, I'm sure that there was nothing to be gained by experimenting on unwitting civilians.
By the way, speaking of population exposures to radiation: In Japan, people still pay good money to bathe in radioactive radon-rich hot springs. [1] It appears that it might even be healthy. [2]
By the way, speaking of population exposures to radiation: In Japan, people still pay good money to bathe in radioactive radon-rich hot springs. [1] It appears that it might even be healthy. [2]
1 - https://misasaonsen.jp/en/radon/
2 - https://pubmed.ncbi.nlm.nih.gov/37635139/